Let us call a function f : A → R anti-continuous if it satisfies the following condition. For every point x ∈ R there exists > 0 and δ > 0 such that for all y ∈ A
0 < |x − y| < δ =⇒ |f(x) − f(y)| > .
(a) Show that there exists an anti-continuous function f : Q → R.
(b) Show that there is no anti-continuous function f : R → R.